CVE-2026-112019 in cgltf
Summary
by MITRE • 10/18/2026
cgltf through 1.15 contains a heap out-of-bounds read vulnerability in cgltf_accessor_unpack_floats() that advances the sparse values cursor by the base bufferView byteStride. Attackers can supply a crafted glTF or GLB file that passes cgltf_validate() to read adjacent heap memory into vertex data or crash applications.
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Analysis
by VulDB Data Team • 10/18/2026
The vulnerability identified in cgltf versions up to 1.15 represents a critical security flaw within the library's handling of sparse accessor data during float unpacking operations. Specifically, the function cgltf_accessor_unpack_floats() contains an implementation error where it incorrectly advances the cursor for sparse values by utilizing the base bufferView byteStride rather than accounting for the actual stride required to access individual elements in a sparse array structure. This miscalculation leads directly to a heap out-of-bounds read condition, allowing the application to retrieve data from memory locations adjacent to the intended target buffer. The severity of this issue is compounded by the fact that the malformed input can successfully bypass the cgltf_validate() function, which serves as an initial gatekeeper for file integrity and structure correctness before processing begins.
From a technical perspective, glTF files often utilize sparse accessors to efficiently store geometry data where most values are zero or default settings. When unpacking these sparse arrays, the library must carefully track offsets within both the base buffer view and the sparse value buffers. The flaw arises because the code assumes that advancing by the byteStride of the base buffer is sufficient for navigating the sparse indices, ignoring the distinct memory layout required to safely read from the separate sparse values array. Consequently, when a crafted glTF or GLB file provides specific index mappings, the pointer arithmetic results in reading beyond the allocated heap region associated with the sparse data structure. This behavior aligns closely with CWE-125, which describes out-of-bounds read vulnerabilities where software reads past the end of a buffer, potentially exposing sensitive information contained within adjacent memory segments or causing instability due to accessing unmapped pages.
The operational impact of this vulnerability is significant for any application integrating cgltf to render 3D content on the web or in native environments. An attacker who can supply a maliciously crafted glTF file has the ability to trigger an out-of-bounds read, which may result in the disclosure of sensitive heap memory contents into vertex data buffers used by graphics rendering pipelines. This could lead to information leakage regarding other applications running within the same process space or internal application states that were not intended for public exposure. Furthermore, if the adjacent memory contains invalid pointers or unaligned data structures, the operation can cause immediate crashes in the host application, leading to denial of service conditions. In complex rendering scenarios, such corruption might also lead to undefined behavior that could potentially be exploited further depending on how the leaked data is processed downstream by graphics drivers or shader programs.
This vulnerability maps directly to MITRE ATT&CK technique T1083, which covers File and Directory Discovery, as an out-of-bounds read can effectively allow an attacker to probe memory layout and discover sensitive information stored in adjacent heap regions. Additionally, it relates to CWE-787, highlighting the risk of accessing memory outside the bounds due to incorrect pointer arithmetic or buffer size miscalculations. To mitigate this risk, developers utilizing cgltf must ensure they are running version 1.16 or later, where the logic for advancing sparse value cursors has been corrected to properly account for element strides rather than relying on base buffer view strides. For applications that cannot immediately upgrade, implementing strict input validation and sandboxing mechanisms can help limit the blast radius of such memory corruption events by restricting access to sensitive heap regions during rendering operations.